The sodium-dependent (“active”) glucose cotransporters (SGLTs), including SGLT1 (found predominantly in the intestinal brush border) and SGLT2 (localized in the renal proximal tubule), have been significantly evaluated. In particular, SGLT2 has been found to be responsible for the majority of glucose reuptake by the kidneys. Inhibition of renal SGLT is now considered a useful approach to treating hyperglycemia by increasing the amount of glucose excreted in the urine (Arakawa K, et al., Br J Pharmacol 132:578-86, 2001; Oku A, et al., Diabetes 48:1794-1800, 1999). The potential of this therapeutic approach is further supported by recent findings that mutations in the SGLT2 gene occur in cases of familial renal glucosuria, an apparently benign syndrome characterized by urinary glucose excretion in the presence of normal serum glucose levels and the absence of general renal dysfunction or other disease (Santer R, et al., J Am Soc Nephrol 14:2873-82, 2003). Therefore, compounds which inhibit SGLT, particularly SGLT2, are promising candidates for use as antidiabetic drugs (reviewed in Washburn W N, Expert Opin Ther Patents 19:1485-99, 2009). In addition, since cancer cells show increased glucose uptake in comparison to their normal counterparts, SGLT inhibition has been proposed as a method for treating cancer by starving cancer cells. For example, studies suggest that SGLT2 plays a role in glucose uptake in metastatic lesions of lung cancer (Ishikawa N, et al., Jpn J Cancer Res 92:874-9, 2001). Thus, SGLT2 inhibitors may also be useful as anticancer agents.
In addition to pharmaceutical activity, a further consideration for the successful development of a medicament is the parameters which are connected with the physical nature of the active substance itself. Some of these parameters are stability of the active substance under various environmental conditions, stability of the active substance during production of the pharmaceutical formulation and the stability of the active substance in the final medicament compositions. In order to provide the necessary stability, the pharmaceutically active substance used in the medicament should be as pure as possible, leading to its stability in long-term storage under various environmental conditions.
The compounds prepared according to the present invention have been prepared previously according to the methods described in WO2001/027128, US2004/0230045, US2005/0124555, US2006/0122126, US2007/0238866, US2007/0275907, US2008/0242596, US2008/0132563, US2008/0318874, WO2008/034859, US2009/0030006, US2009/0030198, US2009/0118201, US2009/0156516, US2010/0056618, US2010/0063141 and WO2010/147430. The aim of the present invention is to provide improved methods for the preparation of such compounds.